Managing the water mass

Minna KalajokiCourtesy of BE GroupThe giant Lossendammen check dam in Central Sweden is one of the country’s major water reservoirs. Built more than half century ago, it was time for an upgrade and safety-enhancing measures. As part of the project, the dam’s new spillway needed new locks, also known as spillway gates.

Future-proof product qualities

The locks are in constant contact with flowing water in harsh climate conditions some 600 kilometers south of the Arctic Circle. They have to withstand all possible water surges and reach a life span calculated in decades and centuries, rather than in years. An additional challenge was their desired shape, which was arched, as opposed to the traditional flat shape.

Outokumpu’s high performance Forta LDX 2101 duplex stainless was chosen for its ultimate product qualities for extreme conditions. The local partner was the Outokumpu Service Center in Degerfors, located 400 kilometers south of Lossendammen.
The grade’s duplex microstructure contributes to high strength and high resistance to stress corrosion cracking and corrosion fatigue – important qualities in dam structures. Due to its elevated content of chromium and nitrogen, duplex stainless offers good resistance to localized and uniform corrosion, while good weldability contributed to achieving the desired arched shape of the locks.

26-tonnes lock

To facilitate the forging work, Outokumpu did all the cutting and bending of the steel plates, before delivering them to a local forging workshop with decades of experience in demanding steel work.

The particular stainless grade enables thinner structures and weight reduction, which was another decisive factor in this project: the two identical lock elements weigh 26 tonnes each. Reduced weight made their handling much easier, both in the workshop and during installation.